Many machines, including off-highway machines, are known to use continuously variable transmissions to drive the ground engaging elements, such as wheels or tracks, of the machine. For example, a hydrostatic drive system commonly includes at least one pump driven by a prime mover, such as an internal combustion engine, of the machine. The pump may be configured to drive one or more sets of motors, which, in turn, power the ground engaging elements of the machine. The pump, and/or motors, may provide variable displacement, such that a fluid flow between the components of the hydrostatic drive system may be adjusted while the machine is running. As a result, direction, speed, and torque of the drive wheels may be continuously varied.
During a typical work cycle, an operator may choose to quickly change the direction, speed, and/or torque, as permitted by the hydrostatic drive system, in order to maximize efficiency in performance of the work cycle. For example, an operator may wish to drive toward a pile of materials at maximum speed, pick up a load of the materials, and quickly reverse away from the pile in order to transport the load to a new location. However, if the operator commands the hydrostatic drive system to accelerate, decelerate, or change directions too quickly, the components of the hydrostatic drive system may not be capable of such quick transitions and, as a result, the machine may jerk or lug. This sacrifice of smoothness for speed may result in a reduction of efficiency caused by, for example, discomfort and fatigue of the operator and/or spilling a portion of the load. Thus, operators may desire a balance of quick responsiveness of the hydrostatic drive system with smoothness in transitions of the hydrostatic drive system. U.S. Pat. No. 6,575,871 to Loeffler et al. teaches a method for controlling an adjusting speed of a shift operation in a continuously variable transmission. Specifically, Loeffler et al. appears to show the division of a shift operation into individual periods. During each period, a desired transmission ratio change is multiplied by a gradient, which is determined in dependence upon various influence quantities, to result in a dynamic desired transmission ratio. The current gear ratio is then transitioned to the dynamic desired transmission ratio at a constant adjusting speed.
The present disclosure is directed to one or more of the problems or issues set forth above.